Hypocalcemia Post Total Thyroidectomy: A Ten-Year, Single Institution Experience with a PTH-Guided Calcium and Calcitriol Supplementation Protocol.

Objective: To report ten-year experience with a parathyroid hormone (PTH)-guided Calcium (Ca) and calcitriol supplementation protocol in reducing the incidence of hypocalcemia after total thyroidectomy (TT).

Methods: Single-institution, retrospective chart review of patients who underwent TT. One hundred forty-eight patients had an operation prior to the protocol introduction and 735 had surgery after the protocol was started. Total serum Ca < 8 mg/dL was defined as hypocalcemia. The 4h-PTH stratified patients into low (>30 pg/mL), intermediate (15-30 pg/mL), and high (<15 pg/mL) hypocalcemia risk groups, to guide Ca and calcitriol management. Demographic information, pre- and post-operative characteristics, and outcomes were recorded. Fisher's exact test and Wilcoxon rank sum test were used to compare the characteristics between the 2 groups. Multivariable logistic regression was used to account for confounding variables. Area under the ROC curve was used to determine optimal 4h-PTH value as predictor of hypocalcemia.

Results: The post-protocol group had significantly lower hypocalcemia incidence (9.9% vs. 20.9%, p<0.001) and related readmissions (0.9% vs. 4.7%, p=0.004) than the pre-protocol group. Lymph node dissection and parathyroids embedded in thyroid tissue were significant risk factors for hypocalcemia. Hypocalcemia occurred in 24.3% of patients with PTH <15pg/mL vs. 2.3% with PTH >30pg/mL. Lymph node dissection and parathyroids embedded in thyroid tissue were significant risk factors. .

Conclusion: A PTH-guided Ca and calcitriol supplementation protocol significantly reduces post-TT hypocalcemia and related readmissions and may represent a useful approach in managing suitable candidates for outpatient TT.